In many ways, they are essentially more of the same, as though the USA were simply turning up their degree of difficulty like a volume dial, one notch at a time.

As Algeria presented many of the same challenges as Slovenia (only more so), Ghana will be a sort of Algeria 2.0. All those things at which Algeria excelled – athleticism, strength, speed, defensive discipline – Ghana does even better.

Then, most likely waiting in the wings will be Uruguay, perhaps this tournament’s king of the whole-is-greater-than-the-sum-of-its-parts soccer – a team on the edge of elite yet so far still pressing its nose against the shop window of soccer greatness.

Ghana, like the USA, remains a step below that but hopeful that Saturday’s game can vault it into a new soccer sphere. The most succinct way to summarize the Black Stars would be this: 1-0. They don’t score much, and they aren’t scored upon much.

They resemble nothing so much as 11 men clenched into an iron fist. In a World Cup that has seen the other top African sides drop out through a lack of organization and collective grit, Ghana has advanced precisely because it has those qualities in abundance.

In some respects, they are Africa’s anti-Africa team, sacrificing style and verve to the cause of cohesiveness and efficiency. In the first round of the World Cup, they conceded two goals in three games – one of them a spectacular German strike from 25 yards out.

Marshaled by two John Mensahs in the center of defense, they stay compact and refuse to let other teams draw them out of position.

The key to unlocking the Ghanaian strait-jacket is similar to the one needed for Algeria: Strong wide play from the USA wing backs to pull defenders out of the center and allow more space for America’s most impressive performer at this World Cup – Michael Bradley – to dominate the midfield.

Offensively, Ghana are still waiting to score their first World Cup 2010 goal from open play. Their two goals in the group stage were both penalty kicks won from handballs in the box.

This is not to say that the game will be as exciting as watching the Fort Knox security cam for 90 minutes. Ghana, at times, can be breathtaking. They are big, strong boys whose physical presence radiates through their soccer.

What they too often lack is that final touch of quality that turns effort and raw skill into the artistry of a well-taken goal. Yet they can often threaten it.

Their greatest danger to the USA is the USA itself, in some ways. Playing with heart and urgency, the USA has been able to twice pull back results after conceding the first goal.

Against Ghana, however, they might need to call in US Army Rangers to blast a way through if they go one-nil down.

Against Ghana, a 1-0 deficit even in the 10th minute could be as much the end of the game as the beginning.